Cisco HWIC-4T1/E1 supports E1 or T1 operation, balanced or unbalanced E1 termination, and CSU/DSU; 4 ports with RJ-48 connectors; Integrated CSU/DSU per port; Balanced or unbalanced E1 termination in the same module; E1 unframed and framed modes (G.703 and G.704); Independent clocking for each port; Multilink PPP or Multilink Frame Relay (FRF.16) for T1/E1 ports on the same module and across different modules.